**Al-Cr-V-N**

Al26Cr24N50 and Al25Cr22V3N50 coatings were deposited by arc evaporation. It was shown that V doping increased the hardness from ca. 31 to 33 GPa, but the oxidation resistance was decreased [100]. Systematic investigations of arc-deposited coatings using (Al70Cr30)1–*x*V*<sup>x</sup>* cathodes with compositions of *x* = 0, 10, 5,20, 25, and 30 at.% showed that the incorporation of V into AlCrN coatings triggers a phase separation into fcc-CrN and hcp-AlN structured grains, even at a low content [101]. Higher bias voltages stabilise the fcc structure.

Cr29.5Al10.5V10N50 sputtered coatings showed a decrease in the friction coefficient at higher temperatures (600 and 800 ◦C) due to phase transformation towards the Magnéli phase V3O7 in pin-on-disc tribometer testing [102].

(AlCrV)N coatings were deposited by arc using Al70Cr30 and Cr70V30 cathodes [103]. The (AlCrV)N coating had a higher hardness and a lower friction value and wear rate than the (Al70Cr30)N coating. The coating containing V showed a higher service life in a milling cutting test. A reason might be the formation of lubricious VO*x* phases.
